Telegraph system



10, 1924. 1,497,287 J. H. BELL TELEGRAPH SYSTEM Filed Dec. 19. 1921 }ToTele hone Patented June 10, 19.24.

' irso STATES p 1,47,87 PATENT o Fic.

JOHN H. BELL, OIE SOUTH ORANGE, NEW JERSEY, ASSIGNOR 'IO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., AOORPORATION' OF NEW YORK.

TELEGRAPH SYSTEM.

Application filed December 19, 1921. Serial No. 523,424.

T 0 all whom it may concern Be it known that I, J OHN H. BELL, a citizen of the United States, residing at South Orange, in the county of Essex, State of New Jersey, have invented certain new and useful Improvements in Telegraph Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to signaling systems and particularly to composite telephone and telegraph systems.

An object of the invention is the provision of means to prevent false operation of the telegraph sounder when signals are be ing transmitted.

In composite systems where the telegraph signals are transmitted bymeans'of the open circuit Morse system, there is a tendency for the recording sounder to give false signals due to the capacity discharge of the electrostatic means, forming a part of the composite equipment, through the home station relay when the key is restored to normal, causing a. large capacity kick at the end of each transmitted impulse.

The invention provides an arrangement whereby upon the restoration of the telegraph key to normal, a leakage path for the electrostatic means forming a part of the composite equipment is established for preventing the false operation of the home station relay by the surge of current produced due to the discharge of such electrostatic means.

There is shown in the drawing a pair of line conductors 4 and 5 with which equipment is associated for permitting simultaneous telegraphic and telephonic communication thereover. Connected in bridge of the line conductors 4 and 5, and as commonly referred to, is composite equipment designed to prevent harmonics produced by the operation of the telegraph equipment from interfering with the operation of the telephone equipment. Connected to one extremity of the line conductor 4, it, of course, being understood that similar equipment is associated with the distant end of this line, is open circuit telegraph apparatus comprising the usual key 6 and home station relay 7, the latter of which controls. the operation of a sounder shown diagrammatically at 8. Similar equipment to that just described is also associated with the line conductor 5 and since such equipment is identical, further description is thought unnecessary here. Between the key 6 and the relay 7 is connected a unit, commonly referred to as a"no-ise killer, comprising an inductance coil 9 and a condenser 10. Also connected to the line conductor 4 and extending to ground is a condenser 11 forming a part of thecomposite equipment which, as previously referred to, tends to prevent disturbing harmonics from interfering with the efiicient operation of the telephone equipment. It is the discharge of the condenser 11 that it is desired to prevent from causing the false operation of the relay 7 upon the restoration of the key tonormal following the transmission of a signal.

The operation of the system is as follows: Assume that telegraph signals are being transmitted over the line conductor 4 in which case the key 6 is operated to connect and disconnect a source of current with the line. Upon the connection of the source of current with the line, the relay 7 is energized for completing the energizing circuit of the recorder 8 which operates to give the transmitting operator an audible signal characteristic of the signal being transmitted. Upon the connection of the source of current with the line, the condenser 11 forming a part of the composite equipment is charged, which charge will be retained until the key 6 is restored to normal or the position shown in the drawing. In the arrangement shown a leakage path is provided for this condenser upon the restoration of the key 6 to normal whereby the capacity kick due to such discharge is prevented from causing the false operation of the relay 7. Consequently recorder 8 will be unaffected upon the discharge of the condenser 11 and no false indication will be given to the operator.

WVhat is claimed is:

1. In a composite system provided for open circuit telegraph operation having a transmitting key with a contact grounded, the method of preventing false operation of the home station relay which comprises establishing from a condenser forming a part of the composite equipment, a leakage path to ground at a contact of the trans- 2. In a signaling system, a pair of line conductors extending between two stations, composite equipment associated with said line conductors" for permitting the simultaneous transmission of telephone and telegraph messages thereover, open circuit telegraph apparatus also associated With said conductors comprising a transmitting key having contacts, one of which isgrounded, and a relay, a condenser forming a part of such composite equipment connected with said conductors intermediate said key and relay, and a leakage path for said condenser established upon the closure of the grounded contact of said key for preventing the camy name this 12th day of December A. D., 20

JOHN H. BELL. 

